Coacting cylinders having skewed gaps to maintain balanced pressure contact



HANTSCHO Jan. 19, 1965 3,166,012

COACTING CYLINDERS HAVING SKEWED GAPS T0 MAINTAIN BALANCED PRESSURECONTACT Filed Aug. 22, 1962 2 Sheets-Sheet 1 INVEILITOR aaegs film/r9090Jan. 19,1965 :5. HANTSCHO 3,166,012

7 COACTING CYLINDERS HAVING SKEWED GAPS T0 MAINTAIN BALANCED PRESSURECONTACT Filed Aug. 22, 1962 2 Sheets-Sheet 2 M p i i A 22 b V T 3 E +40a11 1 l I BLANK 20M: 2.? j T'1. \'!'II +:J-L'T Q L i I I l l f,

{We P1 944061 INVENTO R gray/s H4A/zra/a United States Patent pp3,166,012 COACTING CYLINDERS HAVING SKEWED GAPS T MAENTAEN BALANCEDPRESSURE CONTACT George Hantscho, Tuckahoe, N.Y., assignor to GeorgeHantscho Company, Ina, a corporation of New York Filed Aug. 22, 1962,Ser. No. 218,587 1 Claim. (Cl. 1ll1220) The present invention relates toimprovements in offset printing apparatus.

3,166,012 I Patented Jan. 19,1965.

cooperative transfer or blanket cylinders throughout conketed transfercylinders having narrow blanket securing In the offset printingprocesses as carried out in multistage web presses, the equipment foreach printing stage or station includes a pair of inked plate cylinders,each carrying matter to be printed on the two sides of the paper web,and offset or blanket cylinders for transferring the ink images from theplate cylinders to the paper in the desired registry. The transfersurfaces on the offset cylinders are provided by sheets or blanketswrapped about the cylinders and secured thereto by suitable clampingmeans disposed in transverse slots extending throughout the lengths ofthe rollers. During the actual printing operation, the two blanketcylinders also serve as backing or impression cylinders each for theother, the moving web engaging both in a common narrow transversecontact zone so that both sides of the paper are printed at the sametime. The two blanket cylinders are phased so that theblanket joints ofboth revolve through the common zone and in registry with the spacing ortransverse border area between successive printings or signatures.

It is recognized that for best results in multiple impression work, andparticularly multi-color printing, precise registry of successiveoverlying images is required, calling inrturn for extreme accuracy inspacing and timing between and throughout the apparatus and preventionof slip between the paper and the printing rollers. One difficulty thathas been encountered concerns the gaps in the blanket surfaces createdby the means for fastening the blankets to the blanket cylinders. Thesegaps, which are necessarily of significant width and which as hithertopracticed are phased to pass through the printing zone in simultaneousaxial registry with each other, cause a momentary release of thegripping pressure hetween the cylinders and permit some. slip to occur,To alleviate this tendency, means have been proposed to create frictionbetween the web and the blanket rolls outside the printing zone, forexample, by tilting the tangential plane of the printing zone out ofregistry with the normal plane of the paper web advancing through themachine, thereby causing frictional wrapsof the web about the blanketcylinders before and after passage between the latter. However, inaddition to repeated undesirable distortions of the inked or partiallyinked web from the accurate ideal of straight tangential progressthroughout the various units of the press assembly, such supplementarymeasures in general rely for frictional grip on a small component of thetension of the web itself, which does not alter the fact that theaccurate and powerful pressure grip of the blanket cylinders is stillinterrupted by passage of the straight transversely aligned blanket gapsirrespective of the tangential plane of the print zone.

One object of the present invention resides in the provision of animproved offset printing apparatus adapted to maintain uninterruptedcompressional gripping pressure on a receiving web passing between apair of cooperative blanket cylinders throughout continuous passage ofthe web between the cylinders. V

Another object resides in the provision of an improved offset printingapparatus adapted 'to exert uninterrupted gripping pressure on a webmoving between a pair of joints extending transversely incircumferentially skewed relation to the axes of their respectivecylinders, the cylinders being so rotarily timed as to cause the twoblanket joints to pass through the tially the same time. i a

A further object resides in the provision of printing rollers in whichthe directions of skew of the roller gaps or slots are such as to.permit the two gaps to pass through the tangential zone in substantiallycrisscross relation.

A further object resides in the provisionof printing. rollers in whichthe directions of skewof the roller gaps or slots are such as to permitthe two gaps to pass through the tangential zone in substantialcorrespondence throughout. i

A further object is to provide improved offset printing apparatus forcontinuous web printing including a plurality of successive printingunits each having a'pair. of

zone of tangency at substancooperative transfer cylindersadaptedmutually to maintain uninterrupted gripping pressure on the web.during the entire passage of the web between them, whereby slipbetweenthe web and the units'is preventedthroughout the printingsuccession.

In the drawings: a FIGURE 1 is a vertical sectional view of a typicalpair of blanketed transfer cylinders as applied in a preferred form ofthe invention. l FIGURE 2 is a diagrammatic illustrationof a multipleunit press embodying the invention.

FIGURE 3 is a simplified perspectiveview of a, transfer. cylinderillustrating the skewing of the blanket joint.

FIGURE 4a is a front'elevation of a pair of cooperative offset ortransfer cylinders illustrating the blanket joints as arranged forintersecting. or crisscross operation.

FIGURE 4b is a plan View of the web showing in dotand-dash developmentthe paths of the blanket joints as they pass through the tangentialzone.

across the web when the latter is passed betweencylinders with jointsskewed as in FIGURE .4a.

FIGURE 5a is a view similar to FIGURE 4a but illustrating the blanketjoints as arranged for correspondence FIGURE 5b is a plan view of the,web showing the.

as blanket gap widths and angles of skew have inmost part beenexaggerated in order to. showproperlytheir relationship within theinvention. 'EIG. 6 serves to illustrate the fact that in practice thesefactors, may involve relative dimensions too, small to exhibit therelationships clearly when drawn to the necessary small scale. i i

Referring to FIG. 1, the numerals 20 and 21 generally denote parallelupper and lower rotary offset or transfer cylinders adapted tocompressionally engage a paper web 22 in a common narrow zone oftangency T andto transfer ink images to the top and bottomfaceslof theweb respectively from upper and lowerplate or type cylinders 24 and 25'in the usual offset printing manner. The upper transfer cylinderstructure '29 includes a basic cylinder 26 upon which is wound aperipheral blanket 27 which'provides the actual transfer surface,thelower. cylinder structure 21 similarly including a basic cylinder 28carryinga blanket- 29 The ends of the blankets 27 and 29 are secured intransverse slots or recesses 35 and 31 in their respective basiccylinders; The clamping of the blanket ends within the slots may beaccomplished by any, suitable means such as the structure illustrated,which being per se well known in the ant need only be brieflydescribedas typically applied to blanket 27.-

The respective opposite ends of the blanket are clamped between pairs ofnarrow bars at 32 and. 33. One of the sets of clamping bars 32-isretained in a suitable groove 34 in the Wall of the recess 36, while thesecond set .33 is held in a rotatably adjustable cylindrical clampingmember 35 journalled in a transverse block 36, the block beingsecured inthe basic cylinder by screws 37 and forming in effect an integralportion thereof upon assembly. In set-up, turning the member 35clockwise causes the latter to stretch the blanket 27 and hold it inffirm peripheral engagement with the basic cylinder, 26 In such positiontheclamping member is-locked at the ends of the cylinder by means which,as previously noted, are

. well known in the art and accordingly require no detail descriptionherein. Similarly, as the construction and operation of the'clampingmeans for the lower blanket 29 is. the same asthat described for theupper structure except for rotational direction, further detaildescription of the lowerstructure is omitted .as'undulyrepetitious.

It will benoted, however, that the necessary clearance between the endportions of the upper blanket 27v on emergence from the clamping recess30creates a narrow gap,39-in the true peripheral surfaceof the blanketedcylinder, this'gap extending throughout the width of the blanket. Asimilar gap 40 exists in the case of the lower blanket 29. It. has beenthe presence of'such gaps extending across the blanket surfaces inparallel with the cylinder axesas in the prior art, which has caused theinterruption of compressive gripping pressure on the web and consequentslippage as previously noted. The manncr in which the present inventioneliminates this difli-' cultyis as follows: i f I V 7 Q I ReferringitoFIG. 3, which depicts. the upper blanket cylinder 20, it will be seenthat the gap 39, instead of extending across the blanket in parallelwith the cylinder axis A, is-circumferentially.skewcd so that one edgeof the gap subtends a peripheral arc B ofuninterrupted' peripheralsurface at the rear side. of the blanket 27, this cylinders alwaysremain in mutual compressive relation with the web 22. Thus in thecentral position illustrated in FIG. 4b, the mutual pressure areasextend inwardly for equal distances D from the edges of the web. As theweb continues to move through the zone T, the compressive pressureshifts from the outer areas to the central portion of thefcrisscrosspattern, the shift oc- 1 curring in overlapping relation so that norelease can occur. It will be obvious that a similar overlapping shifthas occurred inreve'rseorder during the entry of the gap combination tothe zone T. Thus, it will be seen that the invention provides aplurality'of operationally overlapping gripping pressure areas spanningthe entire passage of the gaps 39 and 40 through the. zone T,

subtended surface tapering in a triangular area C 'to I the front sideof the blanket. Similarly, the other edge of the gap subtends a secondsurface triangle C tapering to the rear side of the blanket. 1

The peripheral extent of each arc B (defined of course by the widthof-blanket-andthe angle of skew) issuch that throughout. the combinedperipheral extent of the i blanket parallel to the cylinder axis Awithout encountering one or both of the triangular areas C and 0 Inother wordsythe zone T at all times includes a portion of uninterruptedperipheral blanket surface, so that the triangular areas mayappropriately be termed continuity triangles. a

Referring to FIG. 4a, which shows the front or in-feed aspect, the gaps.39 and 40 appearcanted in the'same' direction, though operationallythey areskewed inoppo site directions due to the opposite rotation oftheir respective cylinders, so that as they pass 'conjunctively throughthe pn'ntzone .T, they encounter theweb 22 .two arcs B, no;narrow zone Tcan extend across the maintaining continuity of compressive grip on theweb.

.22 at all times and thereby preventing any possible slip.

The apparatus is so phased that the passage of theblanket joints takesplace in registry with the desired blank'zone. 23 on the webbeingprinted. i In the alternative-arrangement shown in FIG. 5a,. the jointgaps 39 and 4%) are skewedin the same operational direction so as topass through the zone T in correspondence, generating the single slopingpattern 39a-40a illustrated in FIG. 5b. The operation of thisembodimentis thev same as that described above except that theoverlapping shift of compressive pressure application along the zone Ttakes place from a single decreasing area E extending inward fromone'edge of the web 22 to a similar but increasing area E extendinginward from the opposite edge. Obviously this arrangement effectivelymaintains the continuity of compressive gripping pressure withconsequent preventionof slip in the manner set forth.

I As previously noted, the angles of skew have been necessarilyillustrated in exaggerated aspect for purposes of clarity in explainingtheir essential part in the invention. In practice these angles, whichfor any given installation are functions of thegblanket breadth, gapwidth and Width of the contact or printing zone T, are quite small, asillustrated by angle Q in FIG. 6. The width of T, which is theynarrowflattened tangential area in'which the blanket cylinders engage. therweb22, is of course, de-

pendent on the 'cylinder diameters, the applied pressure,

'may be in the order of .3 degree, while fora 48-inch blanket, the skewangle may be significantly smaller.

The extreme smallness of the required skew angles is an advantage inmanufacture, allowing the clamping means to be mounted directly-acrossthe basic cylinders-while confining the skewing to the lips of theclamping recesses, though obviously the illustrated clamping means ortheir equivalent may also be incorporated in skewed position, ifdesired. The skewed gaps may similarly be formed either helically or asstraight lines, the smallness of the peripheral'angles making the twovirtually identical.

' From the foregoing description throughout, it will be evident that bythe introduction of the skewed clamping gaps in the operationalcombination set forth, the invention achieves with maximum simplicityanew and highly in the crisscross pattern illustrated in phantominFIGi4b. Since both the upper and lower skewed gaps subtend pairs ofcontinuity triangles as explained in; connection With FIG. 3, variousperiph'eral areasof the two blanket useful improvement in the offsetprinting art, i.e., the maintenance of uninterrupted gripping pressureon a moving web by the blanketeditransfer cylinders themselves withinthe contact or print zone, eliminating requirement for any otheranti-slip provision and rendering the com bmation particularly welladapted to such advantageous straight tangential multi-unitinstallations as that diagrammatically illustrated in FIG. 2, thoughobviously not as the result of the momentary release of pressure betweencooperating rollers.

Thus, while the invention has been set forth in preferred form, it isnot limited to the exact embodiments illustrated, as variousmodifications may be made Without departing from the inventive conceptwithin the scope of the appended claim.

What is claimed is:

In an offset web printing press, in combination, a blanket transfercylinder including blanket-securing means establishing a transverse gapjoint in the peripheral blanket surface of said cylinder, a secondblanket transfer cylinder disposed in tangential parallelism with saidfirst cylinder and establishing mutually therewith a contact zone ofcompressive gripping pressure on a web passing between said cylinders,and blanket-securing means establishing a transverse gap joint disposedin the peripheral blanket surface of said second cylinder and orientatedto move through said contact zone conjunctively with said first gapjoint, said transverse gap joints being peripherally skewed with respectto the axes of their respective cylinders at predetermined operationallyopposite directional angles, said skewed gap joints move through saidcontact zone in crisscross relationship producing mutual pressure areasextending inwardly from opposite sides of the web and which areasincrease as the central contact area decreases until the gaps are incentered crisscross relationship in the contact zone whereupon saidcentral contact area increases as the side pressure areas decreasethereby effecting a balanced gripping pressure on said web as the gapsmove throughthe contact zone.

References Cited in the file of this patent UNITED STATES PATENTSJohnson May 30, 1961

